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Thin copper plate is widely used in architecture, transportation, heavy equipment, and integrated circuit substrates due to its unique properties. However, it is challenging to identify surface defects in copper strips arising from various manufacturing stages without direct contact. A laser ultrasonic inspection system was developed based on the Lamb wave (LW) produced by a laser pulse. An all-fiber laser heterodyne interferometer is applied for measuring the ultrasonic signal in combination with an automatic scanning system, which makes the system flexible and compact. A 3-D model simulation of an H62 brass specimen was carried out to determine the LW spatial-temporal wavefield by using the COMSOL Multiphysics software. The characteristics of the ultrasonic wavefield were extracted through continuous wavelet transform analysis. This demonstrates that the A0 mode could be used in defect detection due to its slow speed and vibrational direction. Furthermore, an ultrasonic wave at the center frequency of 370 kHz with maximum energy is suitable for defect detection. In the experiment, the size and location of the defect are determined by the time difference of the transmitted wave and reflected wave, respectively. The relative error of the defect position is 0.14% by averaging six different receiving spots. The width of the defect is linear to the time difference of the transmitted wave. The goodness of fit can reach 0.989, and it is in good agreement with the simulated one. The experimental error is less than 0.395 mm for a 5 mm width of defect. Therefore, this validates that the technique can be potentially utilized in the remote defect detection of thin copper plates. [ABSTRACT FROM AUTHOR]

Flour is an essential ingredient in human daily diet, thus it is crucial to measure its moisture content. However, current detection methods are time‐consuming and labor‐intensive, hindering quick measurement. Here we demonstrate the measurement of moisture content in flour via gas in the scattering media absorption spectroscopy (GASMAS) technique. A compact sensor that includes distributed feedback laser driver, cuvette, photodetector, analog lock‐in amplifier, and analysis processing module is developed. We measure the equivalent mean path length of various flour samples, and verify the measurement sensitivity of GASMAS by studying its dependence on moisture content. A linear relationship between path length and moisture content is established by least‐squares curve fitting, corresponding to a correlation coefficient of 0.996. Compared to the drying method, our method shows a maximum error range of 6.1% for all samples, providing a highly accurate and reliable measurement of water content in flour. [ABSTRACT FROM AUTHOR]

The temperature measurement of Sulfur dioxide (SO2) is a crucial parameter for accurately determining its concentration, particularly in high‐temperature environment. Herein, it is realized by using three different techniques, which are direct absorption spectroscopy, wavelength modulation spectroscopy and non‐calibration wavelength modulation spectroscopy based on the bispectral lines temperature measurement method. The bispectral lines of SO2 locates at 1396.844 and 1396.921 cm−1, respectively. The gas temperature in the absorption cell was also measured with K‐type thermocouple and compared with these three spectral measurements. The linearities corresponding to these three techniques are 99.71%, 99.8%, and 99.88%, respectively. Their average relative error between the spectral measurement results and the linear fitting value of the three techniques is 1.15%, 0.86%, and 0.57%, respectively. It is illustrated the feasibility of the bispectral lines method for high‐temperature measurement. These investigations provide methods for temperature measurement in high‐temperature coal‐fired boilers, potentially for investigating other sulfide gas molecules such as SO3 and H2S. [ABSTRACT FROM AUTHOR]

Laser gas sensors with small volume and light weight are in high demand in the aerospace industry. To address this, a coin-sized oxygen (O2) sensor has been successfully developed based on a small toroidal absorption cell design. The absorption cell integrates a vertical-cavity surface-emitting laser (VCSEL) and photodetector into a compact unit, measuring 90 × 40 × 20 mm and weighing 75.16 g. Tunable diode laser absorption spectroscopy (TDLAS) is used to obtain the O2 spectral line at 763 nm. For further improving the sensitivity and robustness of the sensor, wavelength modulation spectroscopy (WMS) is utilized for the measurement. The obtained linear correlation coefficient is 0.9994. Based on Allen variance analysis, the sensor achieves an impressive minimum detection limit of 0.06% for oxygen concentration at an integration time of 318 s. The pressure-dependent relationship has been validated by accounting for the pressure factor in data processing. To affirm its efficacy, the laser spectrometer underwent continuous atmospheric O2 measurement for 24 h, showcasing its stability and robustness. This development introduces a continuous online laser spectral sensor with potential applications in manned spaceflight scenarios. [ABSTRACT FROM AUTHOR]

Squeezing transformation as an essential component of quantum information processing, gives rise to the possibility to perform various tasks such as distributed quantum computation and the quantum‐logic gate. However, the reported squeezing gate with best performance so far is realized with low success probability, while the performance of the deterministic ones is currently circumscribed by the limited squeezing degree of the nonclassical ancilla. To address this issue, a new scheme of deterministic and universal quantum squeezing gate with the property of nonlocal operation owing to the teleportation‐like protocol is developed and demonstrated. A high‐fidelity squeezing operation, even when the level of target squeezing being up to 10 dB, is demonstrated where a squeezed state with nonclassical noise reduction of 6.5 dB is directly observed. Moreover, a high‐fidelity complex operation including a Fourier transformation and a phase squeezing gate are performed, exploring the potential of implementing the complex task of quantum information processing with the presented functional unit. The method can be applied to distributed quantum processor, the creation of exotic nonclassical states, and quantum error correction. [ABSTRACT FROM AUTHOR]

Chlorophyll fluorescence imaging is an effective method of studying the effects of stress on plants. Notably, flooding stress is one of the most important forms of abiotic stress in plants. The present study explored the spatial and temporal variations in the chlorophyll fluorescence parameters in leaves, and analyzed the various response strategies of different plants under flooding stress. We monitored the changes in the SPAD (Soil and Plant Analyzer Development) values, the chlorophyll content and chlorophyll fluorescence imaging. So that the non-destructive measurement of the changes in the physiological state of ten garden shrub species under flooding stress were performed. The results showed that there were significant correlations between the SPAD value and the measured chlorophyll fluorescence parameters (p < 0.05). Additionally, the rank of the tested species based on comprehensive analysis of the flooding tolerance was listed as follows: Hibiscus syriacus > Euonymus kiautschovicus > Chaenomeles speciosa > Lagerstroemia indica > Sorbaria kirilowii > Euonymus japonicus > Lonicera maackii > Rosa xanthina > Amygdalus triloba > Syringa oblata. The findings revealed that the chlorophyll content assumed a continuous downward trend under flooding stress. Moreover, fluorescence imaging illustrated that the leaves of different plants behaved differently under flooding stress given that some showed spotty damaged areas while others were damaged from the leaf margin. Furthermore, the variation in the chlorophyll fluorescence parameters indicated that the flooding tolerance of plants was probably related to the stability of the maximum light quantum yield (QY_max), increase in the steady-state non-photochemical fluorescence quenching (NPQ_Lss) and the time point of the initial increase. [ABSTRACT FROM AUTHOR]

We report on a sequential control scheme to realize a steady, quasi-continuous output of squeezed vacuum states, which eliminates the influence of the seed beam on the squeezing strength. The scheme, originating from time-division multiplexing, separates the generation process from the locking process. We confirm that the sequential control scheme does not reduce the squeezing strength and that the setup operates stably for a 3-h running test, with a duty ratio of 80% and cycle time of 5 s. Therefore, the sequential control scheme opens up a new path of manipulating squeezed vacuum states. [ABSTRACT FROM AUTHOR]